DirectionalLight create cropped shadow for Sprite3D close to the sprite

[Nymzer]

Godot version

3.3.4 stable

System information

GLES3 and GLES2

Issue description

DirectionalLight create cropped shadow for Sprite3D close to the sprite.

OmniLight and SpotLight create proper shadow.

Steps to reproduce

With a simple light setup with shadow enabled, the issue seem to be only with DirectionalLight. The issue occur even with the light shadow bias property set to 0.

To enable the shadow with alpha transparency on the Sprite3D, we need to go in section Flags the property "Alpha Cut" and select the option "Opaque Pre-Pass". The issue occur with all Flags "Billboard" options selected.

Minimal reproduction project

DirectionalLight_Sprite3D_Shadow_cropped_bug.zip

[clayjohn]

This is likely some combination of settings. Try fiddling with bias, shadow range, and normal bias and see if you can get something a little bit better.

[Calinou]

This is likely due to shadow peter-panning caused by the bias values being too high. Try adjusting the DirectionalLight's shadow bias and normal bias values, but note that you won't get a "perfect" result no matter what you do. Decreasing the Shadow Max Distance property can help too.

This is fixed in 4.0 thanks to the introduction of shadow normal offset bias and shadow pancaking. Backporting this work to the 3.x branch is technically possible, but it involves a lot of effort.

Since this issue has been described numerous times already (and is fixed in master), I'll close it.

[Nymzer]

DirectionalLight doesn't have a shadow range. I tried a negative bias of -0.2, I can get something that look better, however if I rotate the light, the bias value doesn't work anymore. If I play with the "Contact" value for the shadow the result I get doesn't look good.

I even tried to create a duplicate Sprite3D only to cast the shadow as suggested on the page below. However having a separate Sprite3D only to cast the shadow from a different position doesn't work once the camera move.
Y-Billboard Sprite3D does not cast shadows : #27738

[Calinou]

DirectionalLight doesn't have a shadow range.

There's a Max Distance property under the Directional Shadow section:

If I play with the "Contact" value for the shadow the result I get doesn't look good.

Contact shadows are known to be broken: #35316

[Nymzer]

Thanks, that I played with the Directional Shadow settings. It didn't removed completely the cropped shadow, however now the space between the shadow and the Sprite3D is smaller and it look much better.